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my new gearbox? (Mazda MX-5 to TR)


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Ups, the adaptors are already delivered, I'm really surprised about the laser cut surface! Tomorrow will be first fit, please keep fingers crossed for me.  

Thanks Russell and Andi, thank you very much, all worked well, fit was 100% on first attempt, the 8 mm drills are exaxtly to the point they have to be for the 5/16" bolts! Btw, the bar is on

Talking of gearbox changes, back in the 8o`s when I was involved with Jaguar racing we converted a V12 XJS from a GM 400 auto box to a Cosworth T6 manual 5 speed by a cut and shut of the two bell hous

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Hi

No I meant if you slide the housing off the shaft, turn it 180 degrees and slight it back on, does it make the gear lever hole closer to the gearbox? Does it HAVE  to be fitted the original way or could you still drill and pin the lever to the shaft this way ? 

 I thought this might make the gear lever hole nearer to the position you need, but without being there I can’t see if there are other reasons you cannot do this ?

Kevin

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Hi Kevin,

sorry me, now I understand.

The shifter housing is resposible to avoid shiftung from gear 5 to R !!!

Turnung the housing 180° this does not effect anymore shifting for 5 to R, this would be possible without problem!

BUT the mechanism would work on gear 1, respectively for shifting from gear 2 to gear 1 (not possible to shift).

So sorry, the answer is NO.

If you want to now how this works see the next photos.

To avoid shifting from 5 direct to R there is a "wing" on the shifter  (the part I had to drill out) and a pin (red), holded in position by a roll pin (blue).

t1n9yXmZLbwnkQHaeVnQD4ixQimqyxh-9uwhB_lR

Turning the shifter housing 180° the left arrow is the position where the pin has to be transformed - but from (now) the rear.

Next you see right side the pin from inside the housing, in the middle the hole for the piston for the 2 steps-resistance on the shifter block,

step 1 = low resistance for N to 5, step 2 = high resistance for N to R, in the case you turning the "wing" back behind the pin.

VP5rbX6v3DztyU_HyHVaJYAMj2LE6vRanljctQTu

Next photo: left the pin, middle the 2-steps piston, right the spring loades ball pushed on the piston.

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So the answer is anyway: No

Last photo:

QUu_tboXj05qVTsIM_5xlD79ySWksvxWSPtlg7mI

Turning it 180° give no benefit.

BUT APART FROM THAT: ANY QUESTION, SUGGESTION OR IDEA IS WELCOME!

Sometimes you don't see the wood for the tress ("same" saying at Germany).

Ciao, Marco

Edited by Z320
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Thank you Marco for taking the trouble to give such a detailed reply. 

I can see that you wouldn’t want to go from 5th to reverse without an issue ( at least until you actually got there anyway ):lol:

Part of the problem of a forum is that you can’t always appreciate the complexities of what someone is trying to achieve at a distance. But you seem to be getting there and good luck!

If I come up with any more brilliant ideas I’ll be in touch :ph34r:

Kevin

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Kevin, you are welcome!

Modifications on the left side are made with a file

iWEKA5ZSLICjFFgGoVvJsKUEV8r4h35_sNrox0tN

Next is to fix the housing the DIY way, means no milling the surface of the gearbox tail (because I do not own a milling machine).

Just an idea, using different files and patience.

Material is ordered but not delivered today...

Edited by Z320
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Some of you might remember this photo, this gave be the idea how to fix the housing on the rear threads,

do you see "the gap"?

enNSNPdlwg5yqg2E0mX3lu4K9HycXCjXzxf_P-nW

its about 4 x 20 mm

FQsk1j19ZJmLynmx6iubZ5EJG34-3YM0h9RyqPSB

going through down under the shifter housing

l5wsucd6V3MJQwVPlX2hb1bNZc9JWP0_Pu0Z5ik6

1st model I made of card board

xoVsCfOLw6IvaxtGtXH4aetM-7rLE38WY1qLmYcr

a "big double T" would also work but the flat area behind the housing is later needed for another reason

cHoVoSdJSs4kMPhvB4-lFbkcVr_UyGNbrr7T6GiR

but the front end is too high for the cross part of the bracket

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this surface left and right has to be reduced for about 4 mm for the "front cross T"

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drilling, using different files, a wooden block as a guide

q0FDsnuAm0ZJyBC_zmXgv1XsgLauxYdNbDzdKzmY

a few minutes job

UmZS0DGpSFT6MJ4I13O-_nN0y6FSz-26OtcGNk-m

patience is helpful

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ready

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fits

gmOpql0ci9iYY-6-mJ0IBl0avQ7hwNt6_4_HJ0QI

next I will make the card board model from steel (drilling, different files, patience)

Edited by Z320
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Looking good so far Marco, a great lesson in what can be done with a bit of thought and as you say patience! Hopefully the rifle bolt action that the MX5 box is famous for will still be there for you once its finished.

Please keep the pics coming.

Andy 

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10 hours ago, PodOne said:

Please keep the pics coming.

Andy 

hmmm, I hope they are not too much.... 

We are now at "chapter 2" off 8 or 9.

But photos are more informative than long explanations....

Edited by Z320
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11 hours ago, Z320 said:

hmmm, I hope they are not too much.... 

We are now at "chapter 2" off 8 or 9.

But photos are more informative than long explanations....

As they say one picture says a 1000 words- so no never too much!

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BTW I have no overdrive on my TR4A and never found its gearbox special heavy.

But currently I have a friends TR gearbox with overdrive on my working bench and wondered about its §$%&"! weight!

Perhaps because old fox Wolfgang let me carry it in the rear end...?

On the scale this evening: 44.0 kg for the TR gearbox with overdrive VS 36.5 kg for the MX-5 gearbox with 5 speed

Just interessting to know? I don't know. 

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  • 2 weeks later...

Hi everybody,

I was out a week on holiday so I have not very much to show you

pFLKWJhQJRW8r68SdKrmKs7alLsXx_BH-sFMqbzj

tvfnIue5kNnLzcdaiWK7sxEq231Y0y9rl28qfv6u

BD0SssVjf-j8t2cBNkJTm2K99W_Gs6ZbqwcpHyq9

The plan is to add later a 3rd fixing from the rear

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yUyguG5hbhr2HuNOqub1NwMRnKff7qW_8oEa9EbP

But next is to cut the selector shaft shorter and re-drill it.

I'm pretty much excited about the quality of the steel....:ph34r:

Ciao, Marco

Edited by Z320
my bad english
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Hi Spyder,

indeed your construction looks some Fred Flintstone like,

but if it works: JABBA DABBA DOO

It this 6 speed gearbox for the lovely car in the background?

:)

Edited by Z320
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31 minutes ago, spyder dryver said:

It sure is!  Here is the gearbox remote in action...

 

https://www.youtube.com/watch?v=WLcTrpQCR7g&feature=youtu.be

Hey Geoff, you're keeping it to yourself ! it says "this video is private".

Mick Richards

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13 hours ago, Motorsport Mickey said:

Hey Geoff, you're keeping it to yourself ! it says "this video is private".

Mick Richards

Now fixed and viewable.

Mick Richards

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Hi there,

to let the tail on the gearbox made sense until this point to get the shorter shifter housing inline with the selector shaft.

And shure it will be possible to cut ite selector shaft shorter and re-drill it with the tail still on the gearbox.

But it will be easier with the tail off, also to cut the casting shorter right side of the gearbox.

I'm very glad Russell follows this project!!!!

Today he guided me to a Youtube video which shows how simple it is to get the tail off and on again.

So this is what I will to next. Russell, thank you very much.

Ciao, Marco

Edited by Z320
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  • 2 weeks later...

Sorry, I did other things the last days,

yesterday I cut off this "ear" from the gearbox housing with my hacksaw and smoothed it with a file...

IdvS2kpggqS41gx9ePT2FDMbLrRWqTyq2y01WopQ

... to get it in this PE box for the case any oil flows out...

SW0dLIrmU32OoZrLKuwdzcf074GZzBqr7SJItgnk

Today I had a fit on the engine to see where the gearbox touches the TR frame.

For this I had to turn the wooden model of the frame "out", later it has to move in again.

Y5uKfProC9oxVW5eRzdmzFxFuL4rsb7-FWUf5ZmI

probably along the black marker line I have to make a cut with my hacksaw

(I know some of you out there have little respect about a hacksaw cut).

9kdQXW6UPaO3Pr9LIoNa-g5bbA3yYkBQlxN2c7yz

to take the tail off was no problem at all, thank you Russell

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some interesting things to see there

YFngRW8W3bkBsVke2j-o8u9OyVb0PFsj9YQgREiW

Next will be to make the selector shaft shorter, perhaps I will not drill it through for a new roll pin,

a grub screw could be better and allows easier to put the assembly in pieces again - if needed?

Ciao, Marco

Edited by Z320
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Hi Marco,

Nice progress.

A grub screw can transmit much lower torque that a roll pin. For final assembly consider a roll pin.
The designer has likely considered this too.

Cheers,

Waldi

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Hi Waldi,

shure you are absolutely right but I was afraid of troubles by drilling the steel of the selector shaft,

but it  this was not the case: it was / is standard steel. See later.

I told you all there are some interesting things to see in the Mazda gearbox.

One of them are these "cracks" in the aluminum casting - this looks horrible?

ZtvW7T6yb0WvWWX76hmAw3pT29SY0YZCIjg2wUfs

But indeed these are lines on the casting, I guess caused be cracks in the sand core while casting.

Some of them are also to see outside - but only very few.

Other detail is this "oil channel" to the rear bearing and the bearing itself.

cJjPl--WzIA5RZUkQIfbr08DsC3UB2hGvBsye5ea

The bearing is not what we know from our TR gearboxes:

it is only a bronze sleeve - for the outer surface of the prob shaft, not the bearbox shaft!

Interesting construction....

Now about the make the selector shaft shorter for about 165 - 8 mm = 157 mm and move the drill for roll pin also 157 mm.

JahhtHDXb2ZItvzC56QPvSoZS3EO5SI-roMomIWA

83Dg0vR7Mw2JTcdxZjHK8LDF33jUVrjK5mRzRruw

Some of you might know how difficult it can be to drill exactly in the center of a round bar,

I learned this while my apprenticeship: make a short piece with the same diameter, pre-drilled on the lathe.

pYSZMZXY5AQmiRXmFFBu1w1dxumhGV5bWiH6EuCf

Fix it in a vice with the round bar exactly at the point where you want to drill it.

Ti0EKinIkgu80Uj4fO9i3y4hxRA6jpMGPoWu0_6l

The 6 mm pin on the end helps me to check the position when it will be parallel to the original drill, first drill I did 3 mm, then 6 mm,

cut shorter with my hacksaw, smoothed the surface with a file, ready. As told above : standard steel, no problem to work with.

XfgYDY5kOjv_PUEAmvE43QtwrJMXW1n0R8H3Mwc4

Ssf7gc0NrjfIcJnqbmqCBSBX2tTp3HJ970PlU9F2

Next will be to make the tube with two seals to connect the selector and gearbox housing oil-sealed.

Ciao, Marco

Edited by Z320
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11 hours ago, Z320 said:

Hi Waldi,

shure you are absolutely right but I was afraid of troubles by drilling the steel of the selector shaft,

but it  this was not the case: it was / is standard steel. See later.

I told you all there are some interesting things to see in the Mazda gearbox.

One of them are these "cracks" in the aluminum casting - this looks horrible?

ZtvW7T6yb0WvWWX76hmAw3pT29SY0YZCIjg2wUfs

But indeed these are lines on the casting, I guess caused be cracks in the sand core while casting.

Some of them are also to see outside - but only very few.

Other detail is this "oil channel" to the rear bearing and the bearing itself.

cJjPl--WzIA5RZUkQIfbr08DsC3UB2hGvBsye5ea

The bearing is not what we know from our TR gearboxes:

it is only a bronze sleeve - for the outer surface of the prob shaft, not the bearbox shaft!

Interesting construction....

Now about the make the selector shaft shorter for about 165 - 8 mm = 157 mm and move thesrill for roll pin also 157 mm.

JahhtHDXb2ZItvzC56QPvSoZS3EO5SI-roMomIWA

83Dg0vR7Mw2JTcdxZjHK8LDF33jUVrjK5mRzRruw

Some of you might know how difficult it can be to drill exactly in the center of a round bar,

I learned this while my apprenticeship: make a shot piece with the same diameter, pre-drilled on the lathe.

pYSZMZXY5AQmiRXmFFBu1w1dxumhGV5bWiH6EuCf

Fix it in a vice with the round bar exactly at the point where you want to drill it.

Ti0EKinIkgu80Uj4fO9i3y4hxRA6jpMGPoWu0_6l

The 6 mm pin on the end helps me to check the position when it will be parallel to the original drill, first drill I did 3 mm, then 6 mm,

cut shorter with my hacksaw, smoothed the surface with a file, ready. As told above : standard steel, no problem to work with.

XfgYDY5kOjv_PUEAmvE43QtwrJMXW1n0R8H3Mwc4

Ssf7gc0NrjfIcJnqbmqCBSBX2tTp3HJ970PlU9F2

Next will be to make the tube with two seals to connect the selector and gearbox housing oil-sealed.

Ciao, Marco

Brilliant stuff Marco.

Rgds Ian

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Hi Ian,

thank you for following this thread and your laud.

Sadly I had to order aluminium bars and seals (in next week) for the connecting tube,

so I decided to plug the drill on the rear end of the shifter housing first.

dp0YHqDueLEX5OYpH1uhMDkdoVg-o2An38hxhamz

Glued with Loctite 638, this should be solid enough to use the rear end as a additional mount.

1b6D5btLAvAlRxGP2XkXbsUfxC63AudEmcbwqFLp

This was the moment to start with chapter 3, to chop the gear box housing.

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This needs mainly patience...., patience..., and patience.

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And if you loved Jerry Lewis, like i did when I was a child, you know what I mean ("The nutty professor", at the gym).

That's it for today.

Ciao, Marco

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Amazing project. I’m so impressed by anyone with engineering skills such as yours Marco even if some off it goes over my head technically. Like at school the pictures help me :unsure:

It’s not just the hands on ability but the idea to start and thinking it through to the end. 
keep up the good work. 
H

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Hi Hamish,

thank you very much for your laud, but I never did that before.

I just grow with the challenges - as you all can grow with your challenges.

Indeed, what is very helpfull is to own good tools and a lathe.

Anythng else you can learn or get help.

Ciao, Marco

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